Talk about looking a gift horse in the mouth. There are many, many men who would love to have their wives perform oral sex on them, but these women refuse, as is their right. Your wife does bring you to orgasm this way and lets you ejaculate into her mouth and you're complaining! I don't think she needs a reason not to swallow the ejaculate. If it bothers her, you should just say thank you and offer her a box of tissues.